Robert W. Wood: Photographing the Invisible, Debunking the Incredible

Robert Williams Wood was born in 1868, much too late to be the inventor of
photography, an honor shared between Nicéphore Niépce, who
produced the
first surviving photograph in 1826, and Louis Daguerre, who subsequently
collaborated with Niépce and sold the process rights to France after
Niépce's death in 1833, who in turn donated them "Free to the
World."

What Wood invented was in a way even more spectacular: whereas
Niépce and
Daguerre merely photographed the visible, Wood was the first to photograph
the invisible images obtained via illumination with ultraviolet and infrared
light. In the process he invented Wood's glass, which blocks visible light
while passing ultraviolet light, thereby making possible today's blacklight
lamps obtainable in hobby and novelty stores and used for Halloween parties
and indoor blacklit miniature golf links.

Besides photography Wood worked on many other aspects of experimental optics,
joining the faculty of Johns Hopkins university in 1901 where he remained
for over half a century until his death in 1955.

At the start of his academic career Wood had already developed something of a
reputation as a debunker of crackpot science. In 1903 physicist
Prosper-René Blondlot, a corresponding member of the French Academy of
Science working
at the Université de Nancy in the west of Alsace-Lorraine, announced a
novel form of radiation that he named N-rays after his institution. Some 120
researchers subsequently confirmed Blondlot's discovery. However a few of
the most famous ones such as Lord Kelvin, William Crookes (of the Crookes
radiometer one sees spinning in novelty science store windows), Otto Lummer
and Heinrich Rubens were inexplicably unable to duplicate Blondlot's results.

Wood was one of these latter, complaining that he'd "wasted a whole morning"
trying to duplicate Blondlot's result. The journal Nature, knowing of
Wood's predilection for debunking, prevailed on him to sail for France in 1904
and visit Blondlot's lab.

Blondlot's demonstration entailed darkening the room in order to see the
effect. Under cover of this darkness Wood removed a crucial prism from the
experiment and asked Blondlot whether the effect was still visible, which
Blondlot cheerfully confirmed. Wood then covertly replaced a metal file
allegedly emitting the N-rays with a wooden object that had been asserted
previously by Blondlot not to emit N-rays. Again Blondlot blithely confirmed
the presence of N-rays.

Wood published his experiences in Nature and the jig was up for Blondlot.
This was a most unfortunate blot on his thus-far highly distinguished
career in which Blondlot had been the first to experimentally confirm in
1891, to within a precision of one percent, that radio waves traveled at
the speed of light, having earlier confirmed that the speed of electricity
in a conductor was not that much slower.

Since N-rays had consumed the scientifically minded public's interest for
the preceding year every bit as much the cold fusion debacle fascinated it
nearly a century later, Wood's reputation with the public as a debunker of
scientific nonsense was cemented forever, quite apart from all his other
many accomplishments.

But no great scientist has made his or her professional reputation on
debunking, any more than Ghandi can be said to have liberated India via
hunger strikes alone. After the N-ray exposure Wood returned to his
more staid research into optical phenomena.

It seems however to be human nature to revisit one's more successful
ventures whatever their nature. And so it was, perhaps, that in
1909 Wood took on two phenomena that he felt were being improperly
explained by his fellow physicists.

One of these was what we call nowadays the greenhouse effect, which
even in those days was well understood as the blocking of heat
by optically transparent materials. Such materials may be solid,
for example glass as first pointed out in 1767 by Swiss physicist
Horace de Saussure (great-grandfather of the philosopher Ferdinand
de Saussure), and nowadays most forms of transparent plastic such
as acrylic and polyethylene, though not TXP which is relatively
transparent to infrared. They may also be liquids such as water,
and gases such as carbon dioxide, methane, and perfume as shown by
noted English physicist John Tyndall during the early 1860s, who
invented the now universally used spectrophotometer for this purpose
and who remarked that the planet's liquid water would be frozen if
the atmosphere consisted only of oxygen and nitrogen, without such
infrared-blocking gases as atmospheric water vapor.

The other effect to whose explanation Wood took exception was a far
more obscure phenomenon associated with the so-called Talbot effect,
in which a diffraction pattern interferes with a finely ruled optical
grating to produce a fascinating array of repeated images at various
periodicities. In the course of studying the Talbot effect, noted
English optical physicist Sir Arthur Schuster had found that the effect
disappeared when a mask was introduced from one side of the apparatus
but not the other. Schuster offered an explanation for this asymmetry,
which as the author of the textbook "An introduction to the theory
of optics" several years earlier he was as well qualified as anyone
in optical physics to do.

Wood published two papers offering alternative explanations of each
of these effects, which he published in respectively the February
(#98) and November (#107) issues of the London and Edinburgh
Philosophical Magazine, or Phil. Mag. as it is affectionately called.

The first of these, amounting to a page and a half describing a casually
performed and documented experiment, is conveniently reproduced at
William Connolley's website, to whom I am indebted for
drawing my attention to Wood's paper on this subject. The second,
a much more carefully reasoned nine-page article, can be seen at Issue
107 of Phil.Mag. via any library with the requisite access
privileges.

Wood found no support whatsoever for either of his theories, quite the
opposite in fact. Both were repudiated in the same journal, in
respectively the July and November issues.

The first was carefully dissected by no less than Charles Greeley
Abbot, then director of the Smithsonian Astronomical Observatory and
later secretary of the Smithsonian Institute from the onset of the
Great Depression to the end of World War II. Abbot's rebuttal, which
can be seen here, was more
than twice the length of Wood's note, describing the observatory's
confirmation of de Saussure's experiment 142 years earlier showing
that three glass plates could produce temperatures 18 degrees above
boiling in a "hot box," and reconciling theory and experiment for
all experiments, both Wood's and the Observatory's, with calculations
that the more experimentally oriented Wood had shown no interest in
carrying out himself.

The second was more quickly disposed of by Schuster, who merely had to
point out in much less space than Wood had needed that the latter had
failed to distinguish coherent from incoherent superposition of light.
This was an easy mistake to make in those days that would however
earn marks off today for any freshman physics student.

Actually it is not entirely true that Wood found no support for his
alternative explanations. After nearly a century during which
physicists and botanists alike continued to teach that trapping
infrared radiation contributed to the heating of greenhouses, climate
historians M.D.H. Jones and A. Henderson-Sellers ran across Wood's
February 1909 paper and notified the climate research community.
Finding Wood's short paper completely plausible as far as they were
concerned, climate scientists proceeded from that point on to teach
that the greenhouse effect for the atmosphere had nothing to do with
greenhouses, which they insisted worked entirely in the manner proposed
by Wood, namely by restricting air circulation. Questions about
the rigor of Wood's work or its subsequent acceptance or rejection
went unraised.

As I wade now through the many Wikipedia pages concerning facets of
climate change---the articles, the talk pages where questions about
the articles are raised, and the administrative pages where judgment is
passed on incivilities---I am struck by a major war and a minor battle.

The war is with the completely understandable vested interests of
those protesting any interference with the ongoing addition of carbon
dioxide to the atmosphere. Those interests have a fiducial duty
to their stockholders to preserve the value of their investments,
without which their companies' stock is put at risk.

The less understandable battle is between the climate scientists who
band together to defend themselves from these vested interests and the
physicists and mathematicians who routinely make minor corrections
to the physics and mathematics of everyone including their own,
not out of any sense of fiducial duty but simply from a distaste for
inaccuracy in science.

In so banding together against the vested commercial interests, the
climate scientists have developed a mentality in which any
criticism of their work, whether motivated by fiducial duty or
scientific rigor, is perceived as an assault on their integrity as
climate scientists.

My concern is that the failure of the climate research community to
draw this distinction puts their credibility at risk and makes them
that much more vulnerable to the energy industry and its stockholders,
whose complaints about climate research have been increasing both
monotonically and shrilly for quite some time now.

When the physicists and mathematicians cannot get a fair hearing
from the climate scientists, the future of the planet is put at
serious risk.